An electronic controlled throttle system, namely, a drive by wire system is well-known as a system to control a combustion state, power, revolution, etc. of an engine mounted to a vehicle such as an automobile more accurately and precisely than a driver intends to control the accelerator. With this electronic controlled throttle system (the drive-by-wire system), an accelerator pedal and a throttle valve are not connected by an accelerator cable. The engine power is controlled based on electronic signals converted from the depressing amount of the accelerator pedal.
As shown in FIG. 6, which is a graph illustrating the operation of a conventional accelerator pedal apparatus utilized for this system, depressing force and sensor output increase linearly from a resting position to a maximum depressing position. Consequently, there is no play at the beginning of depressing the accelerator pedal with this structure.
Here, without any play in the operation of the accelerator pedal, a vehicle with an automatic transmission, for example, might start abruptly if the throttle valve opens when the driver puts his foot on the accelerator pedal unconsciously without any intention of depressing the pedal. Accordingly, to prevent this phenomenon, the driver needs extra care for the accelerator operation, which causes an unsuitable feeling during the operation of the accelerator pedal in comparison with the conventional accelerator pedal apparatus.
The present invention is devised in light of the abovementioned viewpoints, and the purpose is to provide an accelerator pedal apparatus which is easy to operate and causes no unsuitable feeling during the accelerator pedal operation, with the structure being simple, compact and so on.